On an ocean liner bound to Brazil, Lisa, the wife of a German diplomat sees a fellow passenger whom she recognises as Marta, a Polish prisoner from the Auschwitz concentration camp. Lisa is shocked because she thought that Marta was dead. Because of this encounter, Lisa reveals her husband Walter that she was an SS overseer during the war. In flashbacks we are told about what happened in Auschwitz and about the "relation" between Lisa and Marta.